1. Field of the Invention
The present invention generally relates to an optical control for a human machine interface.
2. Description of Related Art
For automotive applications, as well as other environments, mechanical controls are typically used to provide input to an electrical system. Over time, the mechanical controls may wear or collect debris impeding the performance of the controls. Typically, these controls are moved, for example rotated or displaced, to provide user input to the system. Common controls could include knobs, levers, and switches. Recently, other sensing technologies have been investigated to replace controls that require mechanical movement. Some of the technologies investigated include resistive, capacitive, direct optical, and infrared, as well as microwave and magnetic inductance. Each of these approaches reveal a variety of feasibility issues. Although some of these technologies are currently available, their cost and form factor complicates designing them into the automotive interior environment efficiently. In addition, vehicle occupants should be able to identify the control at night in the dark. Accordingly, the control should be lit to help identify its location.
Automotive interiors pose many constraints that limit the use of the above mentioned technologies. Aesthetics, space, and cost concerns usually filter out the above mentioned choices. For example, touch panels typically use resistive technology, however, these devices are typically too large for automotive consoles and not compatible with the aesthetics of the automotive environment. Capacitive technologies are not compatible with vehicle occupants wearing gloves. Direct optical technologies are generally sensitive to varying day and night driving conditions. Infrared controls may be sensitive to vehicle occupants wearing gloves and have unacceptable response times. Other inductive techniques may lead to difficult packaging feasibility, as well as, electromagnetic noise issues.
In view of the above, it is apparent that there exists a need for an improved optical control for a human machine interface.